Dennis Quaid told Conan O’Brien Thursday he gained about “25 to 30 pounds” to play former President Bill Clinton in preparation for The Special Relationship, an HBO movie about the ex-commander in chief.

“I gained about 25, 30 lbs,” Quaid, 55, sporting a youthful, Zac Efron-esque hairdo, said. “And that consisted of having eight meals a day, and at least once, going to McDonald’s — except I didn’t jog there, like he did.”

When O’Brien asked him if the diet helped him get into character, Quaid deadpanned — with a perfect impression of the former president — “Yes you do, very quickly.”

Special Relationship also stars Julianne Moore as Hillary Clinton, and Michael Sheen as former British Prime Minister Tony Blair.